Link, node, shapepoint

[Petros]

http://i.imgur.com/gM3NHtO.jpg



Link Σύνδεσμος: η τυπική μονάδα μέτρησης που αντιπροσωπεύει τη γεωμετρία της οδού μεταξύ δύο διασταυρώσεων.

Node Κόμβος: η διασταύρωση των 2 συνδέσμων (π.χ. μια διασταύρωση)

Shapepoint: ένα σημείο κατά μήκος ενός συνδέσμου που χρησιμοποιείται για να ρυθμίσετε την καμπυλότητα της γεωμετρίας του

[Petros]

Μερικές ακόμα λεπτομέρειες στα Αγγλικά σχετικά με τους κόμβους.

From Node and To Node
In addition to identifying the two end nodes, the Edge record contains fields identifying one of
these nodes as the From Node and the other as the To Node of the edge.
From Node and To Node are identified using the following Rules
•The From Node is the node with the lower latitude. See example 1 in Figure 2-1 where A is the From Node.
•If the latitudes of both end nodes are identical and their longitudes differ, the From Node is determined by the end node with the lower longitude. See example 2 in Figure 2-1 where A is the From Node.
•If, however, the latitudes and longitudes of both end nodes are identical but their Z co-ordinates are different, the From Node is determined by the end node with the lower Z co-ordinate. See example 3 in Figure 2-1.
http://i.imgur.com/OM4MWUr.png
Figure 2-1
•The To Node and From Node of an edge may be the same node. This is called a teardrop. A teardrop edge always contains at least two shape points. Teardrops are only valid for features other than Road Elements. The XYZ Co-ordinates for the end nodes of a road element will never be equal. Additional nodes will be added to avoid teardrop situations on road elements. See Figure 2-2.

http://i.imgur.com/BMsWq30.png


Side orientation is established using the From Node and To Node. The From Node is located at
the "beginning" of an edge. The To Node is located at the "end" of an edge. Side orientation is
used to assign sides to an edge. The "right side" of an edge is the side on the right when facing
the To Node, or "end" of an edge, from the From Node, or "beginning" of the edge. The right and
left sides of an edge are used to assign attributes such as address ranges and administrative area
information. In the XYZ Record, the shape points are listed in sequential order starting at the
From Node end and going to the To Node end. The orientation for a teardrop edge is always
clockwise.